An image forming apparatus using electrophotography is an apparatus for forming an image by forming electrostatic latent images on outer circumferential surfaces of uniformly charged photoreceptor drums and visualizing the electrostatic latent images using toners. In the image forming apparatus which develops an image using a 2-component developer including a toner and a carrier, the toner and the carrier are mixed and stirred by an agitating means provided in a developing apparatus to achieve a uniform ratio thereof. In addition, for a long life of the developer, a trickle development scheme for mixing a new carrier with a new toner before the toner is replenished into a developer container, and overflowing the old developer based on an increase in volume of the developer inside the developer container to discharge the developer from a developer discharge port is employed.
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